Such a power steering system normally has an adjusting mechanism that can swivel at least one vehicle wheel via a steering linkage, a steering wheel that is coupled to the adjusting mechanism and predefines a set point for the steering direction, as well as a drive means to provide steering assistance so as to reduce the torque that has to be applied to the steering wheel in order to adjust the vehicle wheel. With a hydraulic power steering system, the drive means normally provided is a servo pump that is driven by an electric motor and that provides a hydraulic oil flow. With an electric power steering system, the drive means provided is an electric motor that is coupled to the adjusting mechanism.
In order to prevent the adjusting mechanism from striking against an end stop at high speed after a full steering wheel turn angle, a hydraulic power steering system normally has stop valves that are opened when the piston of a hydraulic cylinder, in which the hydraulic oil flow is converted into a steering assistance force, approaches an end position. In this manner, the pressure in the hydraulic cylinder is reduced in time so that the reaching of the end position does not result in excessive mechanical stress and corresponding wear and tear.
The object of the invention is to provide a method of controlling a power steering system in which there can be prevented with low expenditure that the adjusting mechanism reaches an end position with a high steering assistance force.